Zinner et al. (2007) examined conflicting results in the genetic analysis of sportive lemurs in northwest Madagascar, those within the range of what once considered to be Lepilemur dorsalis. Since the type localities of L. dorsalis Gray, 1871 and L. grandidieri Forsyth Major, 1894, were both “Northwest Madagascar”, the proper name of one or two of the new species from the region (sahamalazensis, grewcocki, mittermeieri, tymlerachsoni) could be either of these two. The true "dorsalis", as such, had not been identified, and no attempt has been made to identify grandidieri, formerly a junior synonym of dorsalis. Genetic analysis of the holotypes of dorsalis and grandidieri is needed to resolve this. Zinner et al. (2007) indicated, therefore, that tymerlachsoni and/or mittermeieri might be junior synonyms.

Justification:
The extent of occurrence (EOO) of this speciescovers less than 1,260 km2. This geographic range is severely fragmented and undergoing continuing decline in area, extent and quality of habitat. The number of mature individuals is also known to be in decline. Based on these premises, the species is listed as Endangered.

This species is known only from the Ampasindava Peninsula in northwestern Madagascar. The precise limits of distribution are unclear, especially relative to L. sahamalazensis and L. dorsalis (Rabarivola et al. 2006). The extent of occurrence (EOO) is estimated to be less than 1,260 km2.

This species is threatened by habitat loss and degradation from unsustainable agricultural practices, charcoal production (a particular problem on the Ampasindava Peninsula), as well as mining and unsustainable levels of hunting.

Listed on CITES Appendix I. Not currently known from any protected areas, but may occur in the northern mainland part of the Sahamalaza-Iles Radama National Park. The remaining forest on the Ampasindava Peninsula should be considered for inclusion within a protected area. Further work is now urgently needed to clarify the distribution and taxonomic limits of the recently described Lepilemur species.